### C program to check if a year is leap year or not :

To check if a year is *leap year or not*, we need to check if it is *divisible by 4 or not*. A year is *leap year* if it is divisible by *4* and for century years, if it *also divisible by 400*. In this example, we will learn how to check if a year is leap year or not in *C programming language*. Let’s take a look into the *algorithm* first :

### Algorithm to check if a year is leap year or not :

1. Check if it is *divisible by 4*. If not than it is *not a leap year*.

2. If *divisible by 4*, check if it is *divisible by 100*. If not , it is not a century year, so it *is a leap year*.

3. If divisible by 100, check *if it is divisible by 400 or not*. If yes *it is a leap year*, else not.

List of leap years from *1900* to *2020* are : *1904, 1908, 1912, 1916, 1920, 1924, 1928, 1932, 1936, 1940, 1944, 1948, 1952, 1956, 1960, 1964, 1968, 1972, 1976, 1980, 1984, 1988, 1992, 1996, 2000, 2004, 2008, 2012, 2016, 2020 . *

Let’s take a look into the program :

#include #define LEAP_YEAR 1 #define NON_LEAP_YEAR 0 int checkLeapYear(int year){ if(year%4 == 0 ){ if(year%100 == 0){ if(year%400 == 0){ return LEAP_YEAR; }else{ return NON_LEAP_YEAR; } }else{ return LEAP_YEAR; } }else{ return NON_LEAP_YEAR; } } int main() { int year; printf("Enter a year to check : \n"); scanf("%d",&year); if(checkLeapYear(year) == LEAP_YEAR){ printf("Entered year is a leap year."); }else{ printf("Entered year is not a leap year."); } return 0; }

We can also simplify the *checkLeapYear* function as below :

#include #define LEAP_YEAR 1 #define NON_LEAP_YEAR 0 int checkLeapYear(int year) { if(((year%4==0) && (year%100!=0)) ||(year%400==0)){ return LEAP_YEAR; }else{ return NON_LEAP_YEAR; } } int main() { int year; printf("Enter a year to check : \n"); scanf("%d",&year); if(checkLeapYear(year) == LEAP_YEAR){ printf("Entered year is a leap year."); }else{ printf("Entered year is not a leap year."); } return 0; }

### Sample Output :

Enter a year to check : 2018 Entered year is not a leap year. Enter a year to check : 1984 Entered year is a leap year. Enter a year to check : 2000 Entered year is a leap year.

The output is same for both of these program.